The influence of preparation conditions on the electrical conductivity of poly-N-methylpyrrole films

Electro-active poly-N-methylpyrrole (PNMP) films have been galvanostatically polymerized under a range of conditions. The influence of the conditions used in electropolymerization, such as electrolyte concentration, current density, type of doping anion. and temperature during polymerization on the electrical conductivity has been investigated. The conductivity was measured by the in situ method using a specially prepared two-band microelectrode. The current density used during the polymerization has a considerable influence on the conductivity, as earlier observed for polypyrrole in non-aqueous electrolytes. The conductivity changes with the size of the anion and the concentration of the electrolyte as well as on the temperature at which the polymerization was carried out. Polymer films formed at relatively higher temperatures had lower conductivities and were not able to insert as many counterions, indicating that the films formed were less perfect. At higher temperatures the increased rates and numbers of side reactions may be competing with the ideal one-dimensional polymerization process. (C) 1999 Published by Elsevier Science B.V. All rights reserved.